Almost a decade ago, Alvin Plantinga articulated his bold and controversial evolutionary argument against naturalism. This intriguing line of argument raises issues of importance to epistemologists and to philosophers of mind, of religion, and of science. In this, the first book to address the ongoing debate, Plantinga presents his influential thesis and responds to critiques by distinguished philosophers from a variety of subfields. Plantinga's argument is aimed at metaphysical naturalism or roughly the view that no supernatural beings exist. Naturalism is typically conjoined with evolution as an explanation of the existence and diversity of life. Plantinga's claim is that one who holds to the truth of both naturalism and evolution is irrational in doing so. More specifically, because the probability that unguided evolution would have produced reliable cognitive faculties is either low or inscrutable, one who holds both naturalism and evolution acquires a defeater for every belief he/she holds, including the beliefs associated with naturalism and evolution. Following Plantinga's brief summary of his thesis are eleven original pieces by his critics. The book concludes with a new essay by Plantinga in which he defends and extends his view that metaphysical naturalism is self-defeating.